Use of a crosslinkable silicone invert emulsion for producing breathable coatings

ABSTRACT

The invention relates to the general field of silicone coating on various pliable supports, for example textiles, made of synthetic polymers (polyamide, polyester, etc.). An aim of the invention is to propose an effective process for producing coatings that are waterproof and permeable to moisture vapour, on pliable supports, this process allowing an improvement in the moisture vapour-permeability of the silicones while at the same time conserving the waterproofness. The process according to the invention which achieves this aim consists essentially in coating one of the faces of the support with a film formed by a water-in-oil inverse silicone emulsion comprising a continuous oily silicone phase φs, which can be crosslinked into an elastomer and which comprises a polyorganosiloxane (POS) A that is crosslinkable by polyaddition, by polycondensation, by cationic means or by free-radical means; optionally a crosslinking organosilicic compound B; optionally at least one catalyst C, an aqueous phase φa, a stabilizer, and in seeing to it that the silicone phase φs crosslinks and that removal of water occurs. The invention also relates to pliable supports made of polyamide or polyester, that are waterproof and permeable to moisture vapour, obtained by using a water-in-oil inverse silicone emulsion.

The invention relates to the general field of silicone coating onvarious pliable supports, for example textiles, made of syntheticpolymers (polyamide, polyester, etc.).

More precisely, the invention relates to the coating of pliable (orflexible) materials with liquid compositions containing one or morepolyorganosiloxanes (POS) that are crosslinkable by polyaddition, bypolycondensation, by cationic means or by free-radical means, so as toform a protective film or coating having especially breathablewaterproof (permeable to moisture vapour but impermeable to water)and/or hydrophobic properties.

The pliable supports, in particular textile supports, which can becoated with films made of crosslinked silicone elastomers are, forexample, fabrics for clothing.

The web of pliable supports is coated on at least one of its faces witha silicone film which can be crosslinked, with the aid of means foractivating the crosslinking arranged downstream of the coating head.These means for activating the crosslinking can be heat emitters,radiation (e.g. UV) emitters or electron beam emitters, inter alia.

In the clothing industry, technical fabrics industry or furnitureindustry, there exists a constant need for materials which do not allowwater, but only moisture vapour, to pass through. Being protectedagainst water, whether it comes from the outside, such as rainwater, orfrom the inside, such as moisture vapour from perspiration, destined forrapid condensation, is in fact a particularly important element ofcomfort for users. To avoid this coming into contact with water, thetextile barrier should allow rapid evacuation of the endogenous waterwhen it is in vapour form before it condenses, and should oppose thepenetration of the exogenous water, even when said water is under(slight) pressure.

Besides its performance levels of impermeability to liquid water and of“breathability” with respect to moisture vapour, other properties arerequired for the pliable supports, in particular textiles, namely inparticular: permeability to air, beading effect, etc.

In order to be able to be “breathable waterproof”, a pliable supportmust be pierced with millions of quite small pores so as not to allowdroplets of water to pass through but only to allow water in the form ofvapour to pass through.

Two techniques are used to obtain this property: laminating and coating.

Laminating consists in laminating a porous very fine membrane onto theouter layer of the piece of clothing (2 layers) or between the outerlayer and the lining (3 layers, for example GORE®).

Moreover, coating consists in passing a coating over the piece ofclothing, on which microholes will allow moisture vapour to passthrough. The coating film may, for example, be made of microporouspolyurethane.

A certain number of patents exists which relate mainly to microporous“breathable waterproof” pliable supports (membranes), that arewaterproof and permeable to moisture vapour, made of expandedpolytetrafluoroethylene (for example US-B-5,948,707; US-B-4,187,390;US-B-3,953,566; US-B-4,194,041; WO-A-99/39038), or based on polyurethane(for example EP-A-0 503 826).

Silicones are used in these productions comprising microporous“breathable waterproof” membranes.

Firstly, the involvement of the silicones can be to form coatings whichmake the supports impermeable. This is illustrated by EP-A-0 503 826,which describes novel organosilicone compounds, neopentasiloxanes,Si(OSiR²Q)₄ with Q consisting of ethylene oxide and/or propylene oxideunits, and the use of these silicones in the formation of a film that iswaterproof and permeable to moisture vapour. In fact, polyurethanemembranes suffer from a low resistance to abrasion and a loss ofwaterproofness when the permeability to moisture vapour increases.According to EP-A-0 503 826, the use of these organosilicone compoundsas co-ingredients in the polyurethane coatings makes it possible toincrease the performance levels of the latter.

As described in WO-A-01/26495, silicones can also be used toimpermeabilize seams.

According to US-B-5,948,707 silicones can contribute to improving themechanical properties of microporous “breathable waterproof” membranes.This patent relates more precisely to an expanded PTFE membrane in whichone of the faces is covered with a discontinuous elastomeric coatingwhich introduces non-slip properties by substantially increasing thefriction coefficient.

WO-A-91/17205 discloses the use of crosslinkable or non-crosslinkableelastomeric silicones for producing interpenetrating matrices of PTFEresin and of silicone and thus improving the physical characteristics ofthe material. These structures are microporous, waterproof and permeableto moisture vapour, with improved physical characteristics andresistance to detergents. The silicone penetrates inside the pores,producing a coating of the nodes interconnected by fibrils and of thefibrils themselves.

It emerges from this review of the state of the art that it is unknownto use a silicone elastomer, and even less so a “water-in-silicone oil”emulsion, as essential constituent material of microporous pliablesupports that are waterproof and permeable to moisture vapour.

Nevertheless, the known microporous “breathable waterproof” ready-madegarments comprising silicone can still be improved as regards theirwaterproofness and their moisture vapour-permeability, while at the sametime satisfying economic constraints.

Moreover, improvements are always desirable in economic terms and interms of industrial operating conditions: ease of implementation/hygieneand safety.

Under these circumstances, an essential aim of the invention is topropose an effective process for producing coatings that are waterproofand permeable to moisture vapour, on pliable supports, this processallowing an improvement in the moisture vapour-permeability of siliconeswhile at the same time conserving the waterproofness.

Another essential aim of the invention is to propose an economical,readily implemented and safe process for producing coatings that arewaterproof and are permeable to moisture vapour, on pliable supports.

Another essential aim of the invention is to propose a novel siliconestarting material for processes for producing coatings that arewaterproof and permeable to moisture vapour, on pliable supports, thisnovel starting material having to be effective (waterproofness/moisturevapour-permeability) and economical, and easy and harmless to handle.

Another essential aim of the invention is to propose “waterproofbreathable” silicone fabrics which are entirely effective and relativelyexpensive, and which can be manufactured under industrial conditions.

These aims, among others, are achieved by the present invention, whichrelates, first of all, to a process for producing coatings that arewaterproof and permeable to moisture vapour, on pliable supports,characterized in that it consists essentially:

-   in applying to at least one of the faces of the support, so as to    form a film, a silicone-based water-in-oil inverse emulsion    comprising:    -   a continuous oily silicone phase φs:        -   which can be crosslinked into an elastomer        -   and which comprises:            -   -A- at least one polyorganosiloxane (POS) that is                crosslinkable by polyaddition, by polycondensation, by                cationic means or by free-radical means;            -   -B- optionally at least one crosslinking organo-silicic                compound;            -   -C- optionally at least one catalyst for the                cross-linking reaction;    -   an aqueous phase φa comprising at least 20% by weight of water,    -   at least one stabilizer,-   in seeing to it that the silicone phase φs crosslinks and that    removal of water occurs.

This therefore involves using a reactive, film-forming water-in-siliconeoil inverse emulsion to coat a pliable support, for example amicroporous membrane, for the purpose of forming, after crosslinking, asilicone elastomer coating which is itself also microporous.

The inverse silicone-based emulsions consist of droplets of water in acontinuous silicone oil phase. The water-in-oil emulsions according tothe invention do not comprise the water-in-silicone oil emulsionsobtained from silicone elastomers in solution in organic solvents.

They can be obtained by means of emulsification processes well known tothose skilled in the art and which involve mixing an aqueous phase φaand an oily phase φs without or with milling, i.e. with high shear.

Without wishing to be bound to the theory, the principle of thisinvention would therefore be as follows: when coated onto the support tobe treated, the inverse emulsion constitutes a film. The oily phase ofthe emulsion is then crosslinked so as to form the coating and theaqueous phase is eliminated by evaporation (either during thecrosslinking or by heating). The disappearance of the water then resultsin the formation of micropores in the silicone film. It is thereforenecessary to use a reactive silicone oil.

Furthermore, the elimination of the water contained in the emulsiongives the fabric the “breathability”.

If the thickness of the coating is of the size of the particles, theevaporation of the water effectively creates pores, i.e. a directcontact between the outside and the inside of the fabric.

On the other hand, if the coating is thicker than the droplets of water,there will not, a priori, be this contact. However, it is then possiblefor percolation to occur and for “pathways” to be created during theevaporation and to thus allow the moisture vapour to pass through.

The silicone phase φs preferably has a viscosity η at 25° C. of lessthan 2000 mPa·s, preferably of between 100 and 1400 mPa·s, and even morepreferably of between 100 and 800 mPa·s.

The aqueous phase φa preferably comprises from 30 to 90% by weight ofwater, and even more preferably from 40 to 80% by weight of water.

As regards the mean particle size of the dispersed phase (water), it ischosen so as to confer a certain stability on the inverse emulsion. Thismean particle size is not critical. It is preferable for this aqueousphase φa to have a mean particle size defined by its mean diameter D50(in μm) such that:D50≦100.preferably 0.001≦D50≦50.

For the purpose of the invention, the parameter D₅₀ is the median sizeof the granulometric distribution. It can be determined on the graph ofcumulative granulometric distribution, obtained by one of the analyticaltechniques mentioned below, by determining the size corresponding to thecumulation of 50% of the population of the particles. In practicalterms, this granulometric parameter D₅₀ corresponds to the mean maximumsize of at least 50% of the mass of particles under consideration; a D₅₀of 10 μm indicates that 50% of the particles are less than 10 μm insize. The granulometric measurements can be carried out by conventionaltechniques such as sedimentation, laser diffraction (for exampleCOULTER® LSI30: with the proviso of using a cuvette suitable for thismeasurement), optical microscopy coupled to image analysis, etc.

The stabilizer is preferably chosen from the group comprising:

-   -   non-ionic, anionic, cationic, or even zwitterionic surfactants;    -   silicone polyethers;    -   solid particles, preferably particles of silica optionally in        combination with at least one co-stabilizer, preferably selected        from non-anionic, anionic, cationic, or even zwitterionic        surfactants;    -   and mixtures thereof;    -   solid particles optionally in combination with at least one        co-stabilizer being particularly preferred.

The surfactants are chosen more generally as a function of the HLB. Theterm “HLB” (hydrophilic lipophilic balance) denotes the ratio of thehydrophilicity of the polar groups of the surfactant molecules to thehydrophobicity of their lipophilic portion. HLB values are in particularreported in various basic manuals such as the “Handbook ofpharmaceutical excipients, The Pharmaceutical Press, London, 1994”.

The water/silicone emulsions can also be stabilized via siliconepolyethers (Silicone surfactants—Surfactant Science series V86 Ed RandalM. Hill (1999)).

Moreover, since the beginning of the century, solid particles are knownto enable the stabilization of water-in-oil emulsions. The formation ofa water-in-oil emulsion is promoted when the angle of contact betweenthe oil, the solid and the water is greater than 0° C. The addition of aco-stabilizer can make it possible to improve the stability ofemulsions. [Journal of colloid and interface science 213, 352-359(1999)].

As regards the make-up of the continuous oily silicone phase φs, it may,according to a first embodiment, be a composition of the type such asthat which is crosslinkable by cationic means, in the presence of aphotoinitiator and with actinic activation. More precisely, such acomposition may comprise:

-   -A- at least one POS carrying crosslinking functional groups, the    latter being preferably chosen from groups comprising at least one    ethylenically unsaturated function—advantageously acrylate and/or    alkenyl ether—and/or epoxide and/or oxethane,-   -B- optionally at least one silane and/or one POS carrying    functional groups which may or may not be of the same nature as the    crosslinking functional groups of POS A,-   -C- at least one photoinitiator system, preferably chosen from the    onium salts of an element of groups 15 to 17 of the Periodic Table    or of an organometallic complex of an element of groups 4 to 10 of    the Periodic Table,    the crosslinking functional groups being preferably chosen from    groups comprising at least one ethylenically unsaturated    function—advantageously acrylate and/or alkenyl ether—and/or epoxide    and/or oxethane.

Even more preferably, the POSs A are epoxysilicones and/or vinyl ethersilicones which are:

-   -   either linear or substantially linear and consist of units of        formula (I), ending with units of formula (II.1) and (II.2),    -   or cyclic and consist of units of formula (II.1):    -   in which formulae:    -   the symbols R¹ are similar or different and represent:        -   either a linear or branched C₁-C₆ alkyl radical optionally            substituted advantageously with one or more halogens, the            preferred optionally substituted alkyl radicals being:            methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl,        -   or an optionally substituted C₅-C₈ cycloalkyl radical,        -   or an aryl or aralkyl radical optionally substituted:            -   in particular with halogens and/or alkoxyls,            -   the phenyl, xylyl, tolyl and dichlorophenyl radicals                being particularly selected,        -   and, even more preferably, at least 60 mol % of the radicals            R³ being methyls,    -   the symbols Z are similar or different and represent:        -   either the radical R¹,        -   or a crosslinking functional group corresponding to an            epoxide or vinyl ether residue linked to the silicon by            means of a divalent radical advantageously containing from 2            to 20 carbon atoms optionally comprising a hetero atom, at            least one of the symbols Z corresponding to a crosslinking            functional group;            the POSs A most specially envisaged in the context of the            invention are epoxysilicones of formulae (A.I) and (A.II)            below:    -   with        -   X═CH₃; phenyl; cycloalkyl; alkyl; C₁-C₁₈ alkyl; alkenyl;            -   —OH; H; CH₂—CH₂—CH₂—OH; CH₂—CH₂—CF₃; —(CH₂)_(n)—CF₃, n=1                to 20;        -   and Y=    -   a₁, a₂ and b₁, b₂ being defined as follows, in these formulae        (A.I) and (A.II)        -   1≦a₁, a₂ 1≦b₁, b₂    -   preferably 1≦a₁, a₂≦5000 1≦b₁, b₂≦500 and even more preferably        -   1≦a₁, a₂≦1000 1≦b₁, b₂≦100;    -   a₂, b₂ being =0 in formula (A.II) to give the epoxidized        disiloxane (A.III).

According to a preferred characteristic of the invention, the initiatorsC are, for example: triarylsulphonium salts (for example: [aryl]₃S⁺, PF₆such as that sold by the company Ciba Geigy under the name Cyracure® PIUV 6990), or else the onium borates described in European patentapplication No. 0 562 922, the entire content of which is included inthe present application by way of reference. Even more precisely, it ispossible, in practice, to use the initiator having the formula below:

In practice, the initiators for the use according to the invention areprepared very simply by dissolving onium borate or an organometalliccomplex, preferably of onium, in the form of a solid (powder), in asolvent.

According to an alternative with regard to the onium borate, the lattercan be prepared directly in the solvent from a salt (e.g. chloride) ofthe cation (iodonium) and a salt (for example potassium salt) of theborate anion.

Preferably, it is envisaged in accordance with the use according to theinvention that the initiator (PI) will be used in solution in an organicsolvent, preferably chosen from solvents which are proton donors, andeven more preferably from the following group: isopropyl alcohol, benzylalcohol, diacetone alcohol, butyl lactate, esters, and mixtures thereof.As is claimed in French patent No. 2 724 660, organic solvents which areproton donors and which are aromatic in nature (benzyl alcohol), behaveas crosslinking accelerators. It is therefore advantageous to use themto dissolve the photoinitiator.

It should be specified that the expression “effective catalytic amountof PI” is intended to mean, for the purpose of the invention, the amountthat is sufficient to initiate the crosslinking.

In so far as, in practice—as indicated above—, the photoinitiator isadvantageously dissolved in a polar solvent, it is in an amount suchthat its titre in the solution obtained is between 1 and 50% by weight,preferably between 10 and 30% by weight, and even more preferablybetween 15 and 25% by weight.

According to an advantageous feature of the use according to theinvention, the incorporation of the PI in solution into the oilysilicone phase φs is carried out at a rate of 0.1 to 10% by weight ofsolution relative to the final mixture, preferably 0.5 to 5% by weight,and more preferably of the order of 1% by weight.

In practice, the photoinitiator is thus often present in this oilysilicone phase φs before the emulsification. This photoinitiator canoptionally play the role of co-surfactant.

In accordance with a second embodiment corresponding to a mode ofcrosslinking of the silicones by polyaddition, the following productsare chosen as constituents of the silicone phase:

-   -   POS (A′): product having units of formula:        in which:    -   W is an alkenyl group, preferably vinyl or alkyl,    -   Z is a monovalent hydrocarbon-based group, free of unfavourable        action on the activity of the catalyst and preferably chosen        from alkyl groups containing from 1 to 8 carbon atoms inclusive,        advantageously from the groups methyl, ethyl, propyl and        3,3,3-trifluoropropyl, and also from aryl groups and,        advantageously, from the xylyl, tolyl and phenyl radicals,    -   a is 1 or 2, b is 0, 1 or 2 and a+b is between 1 and 3,        optionally at least some of the other units are units of general        formula:        in which Z has the same meaning as above and c has a value of        between 0 and 3, for example between 1 and 3;        dimethylpolysiloxanes with dimethylvinylsilyl ends, copolymers        of methylvinyldimethylpolysiloxanes with trimethylsilyl ends,        copolymers of methylvinyldimethylpolysiloxanes with        dimethyl-vinylsilyl ends and cyclic methylvinylpolysiloxanes        being more specially selected;    -   POS (B′): product having siloxyl units of formula:        in which:    -   L is a monovalent hydrocarbon-based group free of unfavourable        action on the activity of the catalyst and preferably chosen        from alkyl groups containing from 1 to 8 carbon atoms inclusive        and, advantageously, from the groups methyl, ethyl, propyl and        3,3,3-trifluoropropyl, and also from aryl groups and,        advantageously, from the xylyl, tolyl and phenyl radicals,    -   d is 1 or 2, c is 0, 1 or 2, d+c has a value of between 1 and 3,    -   optionally at least some of the other units being units of        general formula:        in which L has the same meaning as above and g has a value of        between 0 and 3, and        (methylhydrosiloxy)(α,ω-dimethylhydro)-poly(dimethylsiloxane)        being more specially selected.

These POSs that are crosslinkable by polyaddition can be of the typesuch as those which crosslink at room temperature or under hotconditions by means of polyaddition reactions in the presence of a metalcatalyst, in this case platinum-based. They are crosslinkable POScompositions referred to as RTV (“room temperature vulcanizing”) or coldvulcanizable elastomers (EVF).

However, it may be desirable, on an industrial level, to accelerate thecrosslinking by increasing the temperature of the silicone layerdeposited onto the pliable support (for example 100-150° C.)/tunnel ovenin an industrial device functioning continuously. This involves thepolyaddition POS compositions referred to as HVE, which is theabbreviation for “hot vulcanizable elastomer”.

The two-component or single-component POS compositions that are RTV orHVE by means of polyaddition, essentially by reaction of hydrosylylgroups on sylylated alkenyl groups, generally in the presence of a metalcatalyst (preferably a platinum catalyst), are described, for example,in U.S. Pat. Nos. 3,220,972, 3,284,406, 3,436,366, 3,697,473 and4,340,709.

According to a third embodiment, the silicone phase can crosslink bypolycondensation of OH groups and/or of hydrolysable groups, in thepresence of a tin catalyst. This is aimed at two-component orsingle-component POS compositions which crosslink at room temperature bymeans of polycondensation reactions under the action of moisture,generally in the presence of a metal catalyst, for example a tincompound (RTV polycondensation).

The POSs which go into making up these RTV polycondensation compositionsare linear, branched or crosslinked polysiloxanes carrying hydroxylgroups or hydrolysable groups, for example alkoxy. Such compositions canalso contain a crosslinking agent, which is, in particular, a cylindercarrying at least 3 hydrolysable groups, such as, for example, asilicate, an alkyltrialkoxysilane or an aminoalkyltrialkoxysilane.

These compositions are described, for example, in U.S. Pat. Nos.3,065,194, 3,542,901, 3,779,986 and 4,417,042 and in patent FR-2 638 752(single-component compositions) and in U.S. Pat. Nos. 3,678,002,3,888,815, 3,933,729 and 4,064,096 (two-component compositions).

Besides these POSs, the liquid silicone coating composition can alsocontain:

-   -   -D- at least one adhesion promoter (D);    -   -E- and/or at least one additive (E) that is common in silicone        compositions which crosslink by cationic means or by        free-radical means, by polyaddition or by polycondensation.

As regards the additives (E), mention may be made of:

-   -   for the POSs that are crosslinkable by cationic and/or        free-radical means or by activation with radiation or electron        beams:        -   epoxy ether diluents,        -   pigments of the type carbon black, titanium dioxide,            phthalocyanin, benzimidazolone, naphthols (BONA pigment            lakes); diazopyrazolones; diarylide or monoarylide yellow            pigments and the like, benzimidazolone, naphthone,            diazopyrazolone, and the like,        -   photosensitizers chosen from poly(aromatic)            products—optionally metallic—and heterocyclic products            (phenothiazine, tetracene, perylene, anthracene,            xanthopinacol, thioxantone, and the like),        -   inhibitors of crosslinking, preferably chosen from alkaline            products, and even more preferably from alkaline products of            the amino type, for example of the type such as those            consisting of a silicone onto which is grafted at least one            amine group, preferably tertiary amine group;    -   for the polyaddition RTV POS compositions:        -   agents which slow the addition reaction (e.g.            tetramethylvinyltetrasiloxane, pyridine, phosphines,            phosphites, unsaturated amides and acetylenic alcohols;    -   for the polycondensation RTV or HVE POS compositions:        -   crosslinking agents such as alkyltrialkoxysilanes, alkyl            silicates, poly(alkyl silicates) (methyl silicate, ethyl            silicate, isopropyl silicate, n-propyl silicate, and the            like);    -   and, in general, for all the POSs:        -   pigments,        -   α-olefins,        -   the fillers, and in particular the silicon fillers, may, for            example, be pyrogenic silicas treated with            hexamethyldisilazanes or with octamethylcyclotetra-siloxanes            (specific surface area 300 m²/g), silica fume.        -    These fillers may or may not be inorganic, e.g.: ground            synthetic or natural fibre (polymers), calcium carbonate,            talc, clay, titanium dioxide, and the like.

As regards the methodological characteristics, an amount of inversesilicone emulsion such that the thickness of the film forming thecoating is less than or equal to 500 μm, preferably between 150 and 300μm, is applied to the support.

According to another of its aspects, the invention relates to the use ofa water-in-oil inverse silicone emulsion, comprising:

-   a continuous oily silicone phase φs:    -   which can be crosslinked into an elastomer    -   and which comprises:        -   -A- at least one polyorganosiloxane (POS) that is            crosslinkable by polyaddition, by polycondensation, by            cationic means or by free-radical means;        -   -B- optionally at least one crosslinking organo-silicic            compound;        -   -C- optionally at least one catalyst for the cross-linking            reaction;-   an aqueous phase φa,-   at least one stabilizer,    for producing coatings that are waterproof and permeable to moisture    vapour, on pliable supports.

Also protected by the invention is any film-forming water-in-oil inversesilicone emulsion, for producing coatings that are waterproof andpermeable to moisture vapour, on pliable supports, characterized in thatit comprises:

-   -   a continuous oily silicone phase φs:        -   which can be crosslinked into an elastomer        -   and which comprises:            -   -A- at least one polyorganosiloxane (POS) that is                crosslinkable by polyaddition, by polycondensation, by                cationic means or by free-radical means;            -   -B- optionally at least one crosslinking organo-silicic                compound;            -   -C- optionally at least one catalyst for the                cross-linking reaction;    -   an aqueous phase φa comprising at least 20% by weight of water,    -   at least one stabilizer,    -   at least one additive which promotes adhesion of the coating to        the support and/or an improvement in the waterproof and moisture        vapour-permeability properties,    -   and/or at least one additive for optimizing the mechanical        properties of the coating. The water-in-oil emulsions according        to the invention do not comprise the water-in-silicone oil        emulsions obtained from silicone elastomers in solution in        organic solvents.

Finally, another subject of the invention consists of a pliable support,preferably textile support, and even more preferably synthetic textilesupport, characterized in that it is coated on at least one of its faceswith a coating that is waterproof and permeable to moisture vapour,obtained by implementing the process as defined above or according tothe use as defined above, or else using the emulsion as defined above.

DESCRIPTION OF THE FIGURES

The attached FIGS. 1 and 2 are graphs giving the permeability P in g/m²over 24 hours of a fabric coated with the water-in-oil inverse emulsion,as a function of the water content in % of the emulsion.

EXAMPLES

The support used in these experiments is made of polyamide (110decitex).

The coating methods are well known to those skilled in the art.

Examples 1 and 2:

Advantage of the coating based on the silicone oil inverse emulsioncompared to the coating with silicone oil alone. TABLE 1 Coating Natureof % Nature of the Example type the oil % oil water stabilization 1 OilA.I with 100 0 — a₁ = 70-80 b₁ = 7-8 and η = 350 mPa · s 2 Inverse A.Iwith 60 40 Silica emulsion a₁ = 70-80 b₁ = 7-8 and η = 350 mPa · s

On a laboratory scale, the oil is introduced into an IKA-type reactorequipped with a scraper blade and a counter blade. The silica isintroduced into the oil with stirring (80-100 rpm). After completedispersion of the silica in the oil, the water is introduced slowly andthe stirring is maintained until the water has been completelyincorporated. When the stirring is stopped, no drop of water should bevisible at the surface.

The stabilization is provided by a hydrophobic precipitated silica (forexample Sipernat® D10 from Degussa).

The photoinitiator is present in the oil before the emulsification, at arate of 0.5% by weight, and combines 0.5% by weight of a cosolventconsisting of isopropanol. The photoinitiator used is that having theformula below:

Evaluation of the permeability:

In an MPC oven or air-conditioned room at 25° C. and 50% relativehumidity, the coated support is placed in a leaktight manner over analuminium crucible containing 150 ml of water, a drop of bactericide anda piece of sponge which makes it possible to avoid any contact betweenthe membrane and the water. The crucible should be placed in theair-conditioned room or the oven for 48 h before measurements start tobe taken. After equilibration, the crucible is weighed regularly every24 hours.

The curve of the loss in mass as a function of time is plotted. Thiscurve should be taken into account when it becomes linear. Thepermeability P can then be calculated in the following way:P=slope/πr ² expressed in g/m²/24 hwith:

-   -   slope in g/24 h    -   r=0.05 m: radius of the surface of exchange through the membrane

The results obtained are as follows: TABLE 2 Permeability ExampleDescription g/m² over 24 h 1 Support + A.I 63 with a₁ = 70-80, b₁ = 7-8and η = 350 mPa · s 2 Support + A.I inverse emulsion 402 with a₁ =70-80, b₁ = 7-8 and η = 350 mPa · s

-   -   The inverse emulsion of crosslinkable silicone oil makes it        possible to multiply by 6.4 the permeability to moisture vapour        of a silicone oil.

Examples 3 to 7

Influence of the water content of the inverse emulsion:

In addition, this test was carried out in order to compare thepermeability provided by emulsions containing various amounts of water:20%, 30%, 45% and 60%. The emulsions are stabilized with 8% silicarelative to the water.

The permeabilities thus obtained are as follows: TABLE 3 Example 3 4 5 67 % water/water + oil 0 20 30 45 60 P g/m² over 24 h 63 72 79 165 402

-   -   It is therefore noted that, the greater the amount of water in        the emulsion, the greater the permeability to moisture vapour        (see attached FIG. 1).

Examples 8 to 10

The permeability to moisture vapour was also evaluated at 38° C. and 50%RH.

The inverse emulsions used for the coating contain from 20 to 60% ofwater.

The results are as follows: TABLE 4 Example 8 9 10 % water/water + oil20 40 60 P g/m² over 24 h 195 699 2292

These results are reported in the attached FIG. 2.

-   -   Given that, in the absence of coating, the support alone results        in a permeability of 3076 g/m² over 24 h, the inverse emulsion        containing 60% of water therefore makes it possible to recover        75% of the permeability of the support.

Examples 11 to 14

The permeability to moisture vapour (23° C., 50% RH) was also tested onclothing fabrics containing cotton and polyester using an inverseemulsion containing 60% of water stabilized with 8% of silica/water.

Overall, the results were as follows: TABLE 5 Permeability Permeabilitysupport alone support + inverse Ratio Examples Support type (1) emulsion(2) (1)/(2) 11 Polyester 1769 705 40% 12 Polyamide 2026 810 40% 13Polyester - 1120 834 74% cotton 67/33 14 Cotton 1497 1000 67%

-   -   Depending on the textile support used for the coating, it is        possible to recover up to 74% of its permeability using an        inverse emulsion.        All these results show that:    -   the use of an inverse emulsion of reactive silicone oil makes it        possible to increase the permeability to moisture vapour of the        oil,    -   to obtain waterproof breathable coatings,    -   the permeability increases with the water content of the inverse        emulsion.

1. Process for producing coatings that are waterproof and permeable tomoisture vapour, on pliable supports, comprising: applying to at leastone of the faces of the support, so as to form a film, a silicone-basedwater-in-oil inverse emulsion comprising: a continuous oily siliconephase φs: which can be crosslinked into an elastomer and whichcomprises: -A- at least one polyorganosiloxane (POS) that iscrosslinkable by polyaddition, by polycondensation, by cationic means orby free-radical means; -B- optionally at least one crosslinkingorganosilicic compound; -C- optionally at least one catalyst for thecrosslinking reaction; an aqueous phase (pa comprising at least 20% byweight of water, at least one stabilizer, in seeing to it that thesilicone phase φs crosslinks and that removal of water occurs. 2.Process according to claim 1, wherein the silicone phase φs has aviscosity η at 25° C. of less than 2000 mPa·s.
 3. Process according toclaim 1, wherein the aqueous phase φa comprises from 30 to 90% by weightof water.
 4. Process according to claim 1, wherein the continous oilyphase the aqueous phase φa has a mean particle size defined by its meandiameter D50 (in μm) such that:D50≦100.
 5. Process according to claim 1, having an amount of inversesilicone emulsion such that the thickness of the film forming thecoating is less than or equal to 50 μm applied to the support. 6.Process according to claim 1, wherein the stabilizer is selected fromthe group comprising: non-ionic, anionic, cationic, or even zwitterionicsurfactants; silicone polyethers; solid particles, preferably particlesof silica optionally in combination with at least one co-stabilizer; andmixtures thereof; the solid particles optionally in combination with atleast one co-stabilizer.
 7. Process according to claim 1, wherein thecontinuous oily silicone phase φs comprises: -A- at least one POScarrying crosslinking functional groups, the latter being selected fromgroups comprising at least one ethylenically unsaturated function; -B-optionally at least one silane and/or one POS carrying functional groupswhich may or may not be of the same nature as the crosslinkingfunctional groups of POS A; -C- at least one photoinitiator systemselected from the onium salts of an element of groups 15 to 17 of thePeriodic Table or of an organometallic complex of an element of groups 4to 10 of the Periodic Table; the crosslinking functional groups beingselected from groups comprising at least one ethylenically unsaturatedfunction and/or epoxide and/or oxethane.
 8. Process according to claim7, wherein the POSs A are epoxysilicones and/or vinyl ether siliconeswhich are: either linear or substantially linear and comprise units offormula (I), ending with units of formula (II.1) and (II.2), or cyclicand consists of units of formula (II.1): in which formulae: the symbolsR¹ are similar or different and represent: either a linear or branchedC₁-C₆ alkyl radical optionally substituted advantageously with one ormore halogens, or an optionally substituted C₅-C₈ cycloalkyl radical, oran aryl or aralkyl radical optionally substituted: with halogens and/oralkoxyls, the phenyl, xylyl, tolyl or dichlorophenyl radicals, thesymbols Z are similar or different and represent: either the radical R¹,or a crosslinking functional group corresponding to an epoxide or vinylether residue linked to the silicon by means of a divalent radicalcomprising from 2 to 20 carbon atoms optionally comprising a heteroatom, at least one of the symbols Z corresponding to a crosslinkingfunctional group, the POSs A most specially envisaged beingepoxysilicones of formulae (A.I) and (A.II) below:

with X═CH₃; phenyl; cycloalkyl; alkyl; C₁-C₁₈ alkyl; alkenyl; —OH; H;CH₂—CH₂—CH₂—OH; CH₂—CH₂—CF₃; —(CH₂)_(n)—CF₃, n=1 to 20; and Y=

a₁, a₂ and b₁, b₂ being defined as follows, in these formulae (A.I) and(A.II) 1≦a₁, a₂ 1≦b₁, b₂ a₂, b₂ being =0 in formula (A.II) to give theepoxidized disiloxane (A.III).
 9. Process according to claim 1, whereinthe following products are selected as constituents of the siliconephase: POS (A′): product having units of formula:

in which: W is an alkenyl group, Z is a monovalent hydrocarbon-basedgroup, free of unfavourable action on the activity of the catalyst andselected from alkyl groups containing from 1 to 8 carbon atomsinclusive, and also from aryl groups a is 1 or 2, b is 0, 1 or 2 and a+bis between 1 and 3, optionally at least some of the other units areunits of general formula:

in which Z has the same meaning as above and c has a value of between 0and 3; dimethylpolysiloxanes with dimethylvinylsilyl ends, copolymers ofmethylvinyldimethylpolysiloxanes with trimethylsilyl ends, copolymers ofmethylvinyldimethylpolysiloxanes with dimethylvinylsilyl ends and cyclicmethylvinylpolysiloxanes being more specially selected; POS (B′):product having siloxyl units of formula:

in which: L is a monovalent hydrocarbon-based group free of unfavourableaction on the activity of the catalyst and selected from alkyl groupscomprising from 1 to 8 carbon atoms inclusive and d is 1 or 2, c is 0, 1or 2, d+c has a value of between 1 and 3, optionally at least some ofthe other units being units of general formula: in which L has the samemeaning as above and g has a value of between 0 and 3, and(methylhydrosiloxy)(α,ω-dimethylhydro)-poly(dimethylsiloxane) being morespecifically selected.
 10. A method for producing coatings that arewaterproof and permeable to moisture vapor comprising a water-in-oilinverse silicone emulsion, comprising: a continuous oily silicone phaseφs: which can be crosslinked into an elastomer and which comprises: -A-at least one polyorganosiloxane (POS) that is crosslinkable bypolyaddition, by polycondensation, by cationic means or by free-radicalmeans; -B- optionally at least one crosslinking organosilicic compound;-C- optionally at least one catalyst for the crosslinking reaction; anaqueous phase φa, at least one stabilizers.
 11. Film-formingwater-in-oil inverse silicone emulsion, for producing coatings that arewaterproof and permeable to moisture vapour, on pliable supports, whichcomprises: a continuous oily silicone phase φs: which can be crosslinkedinto an elastomer and which comprises: -A- at least onepolyorganosiloxane (POS) that is crosslinkable by polyaddition, bypolycondensation, by cationic means or by free-radical means; -B-optionally at least one crosslinking organosilicic compound; -C-optionally at least one catalyst for the crosslinking reaction; anaquous phase φa comprising at least 20% by weight of water, at least onestabilizer, at least one additive which promotes adhesion of the coatingto the support and/or an improvement in the waterproof and moisturevapour-permeability properties, and/or at least one additive foroptimizing the mechanical properties of the coating.
 12. Pliablesupport, optionally a textile support, which is coated on at least oneof its faces with a coating that is waterproof and permeable to moisturevapour, obtained by implementing the process according to claim 1.